Thank you for the changes to the signals. I adopted them and I am now looking for ways to achieve the goals you suggested without breaking it.

I see that you reduced the number of chain signals to one per section. Definitely cleaner, and on second thought you are right as there is no advantage to having 2 chain signals in a segment. I also see how you use a technique of using regular signals on the outside left turns and turnarounds, I would have never thought of it and it certainly causes trains to "release" a segment faster. Nice.

I did not incorporate lane changing in the design for two reasons. (1) Any built-in lane changer would limit the train sizes the intersection supports, and one of my goals was to ensure that it can support trains of any length without deadlocks, even if much longer trains might slow it down. (2) Less important to an intersection being shared, my overall rail strategy tends to make the pathfinder place the trains in the correct lane sometimes long before reaching the intersection.

Here are some concept designs to achieve what you suggested. I did not place signals as I deleted them right after the screenshots. Let me know if/which you think are worth doing for real:

Right turn on the outer lane
- Small right on the outer straight through square.
- Seems like it would fit quite well, with no negatives that are obvious to me, and probably have a decent impact on right turn throughput.
- Screenshot shown for upper left quadrant.

rightTurnOuterLane.png (2.3 MiB) Viewed 1269 times

Left turns on the inner lane
- Parallel line to the outer one
- Concern: Slightly complicates the outer lane straight through passage.
- Screenshot shown for upper left quadrant.

leftTurnInnerLane.png (4.23 MiB) Viewed 1269 times

Additional waiting bays
- Applies to the outer lanes only.
- Concern: The additional lanes would only be usable by trains up to 4 locomotives/8wagons max, unless the spacing to the lane switcher is widerned.
- Slightly embarassing: Shows my pretty primitive lane switchers. They are not a problem in my base only because of my overall rail strategy that places trains on the desired lanes way ahead of the intersection.

additionalWaitingBay.png (8.26 MiB) Viewed 1269 times

I am pretty comfortable that the Right turn on the outer lane will work and not have a negative impact. I'll start on that one and wait on your opinion before attempting the other two.

I did not incorporate lane changing in the design for two reasons. (1) Any built-in lane changer would limit the train sizes the intersection supports, and one of my goals was to ensure that it can support trains of any length without deadlocks, even if much longer trains might slow it down. (2) Less important to an intersection being shared, my overall rail strategy tends to make the pathfinder place the trains in the correct lane sometimes long before reaching the intersection.

Here are some concept designs to achieve what you suggested. I did not place signals as I deleted them right after the screenshots. Let me know if/which you think are worth doing for real:

Right turn on the outer lane
- Small right on the outer straight through square.
- Seems like it would fit quite well, with no negatives that are obvious to me, and probably have a decent impact on right turn throughput.
- Screenshot shown for upper left quadrant.

Those outer lane right turns would cross each other, you would get the same problem with the outer lane that was with the inner lane in the first version posted.
Ideally, they would go through the center like the inner lane ones.

Additional waiting bays
- Applies to the outer lanes only.
- Concern: The additional lanes would only be usable by trains up to 4 locomotives/8wagons max, unless the spacing to the lane switcher is widerned.
- Slightly embarassing: Shows my pretty primitive lane switchers. They are not a problem in my base only because of my overall rail strategy that places trains on the desired lanes way ahead of the intersection.
additionalWaitingBay.png

Based on what you said of "crossing each other" (which is true) I guess my outer lane right turns are actually going to hurt throughput instead of help. I'll remove them and see if I can think of another way of doing it.

Here is what I meant by adding waiting areas, or buffer or what you want to call them.
Atm the throughput isnt that big, because right turns are limiting it, as all trains going to the right have to drive into the same lane. Adding a lane for the outer lane, like we talked about, would help with that.

set 1 (random) 71 trains/min

You should really be working on your intersection on the test bench, It lets you study your intersection and I have learned a lot from just watching intersections here. I added my savefile so that you can use my setup, your intersection with buffers is on the bench.

Edit: I also made the U-turner better, as it won't dealy other trains as much when it is like this.
Updated the savefile to be a bit more easy to use

I was able to install the Automatic Train deployment and Creative Mode (fix for 0.16) mods and to add your save file. I also see the train counter blueprint (apparently a new version, not the one mentioned in the thread) at the bottom right.

I didn't install Screenshot Camera since I already have a similar screenshot mod. Is that specific one needed?

Also, I am not quite sure how to use this rig. Is there documentation?

For example: How do I start and stop the trains so that I can make changes? How do you choose the set? Is there a list of what each set is? You mentioned ("Set 1 = random", "Set 2 = planned 50% straight, 15% left, 35% right) and "Set 5 = Right turns only" in your posts but that must come from somewhere.

I read pretty much everything in that first post be the links it privides.

The problem is that it gives a lot of information about what he did and all the pieces, but has no clear instructions on how to just USE the testing system. Or if those instructions exist somewhere they are very hard to find.

The lack of instructions in how to use it makes it unusable to test by ourselves.

Some specific problems on using it:.

- It "looks like" you have to set desired parameters in the constant combinators, but there is no simple list of what those parameters are and which are the critical ones to test.

- It is not clear how do you start and stop the system. Or are we simply supposed to cut the tracks to stop it, and restore then to start it?

- It is pretty clear that once you figure out how to start it you need to turn the inserter and it will reset the counter. Then after 15 minutes it will produce a list of results for each set... but it is not clear at all where those results will be.

- Ideally there should be a section (or or better yet a link to an instructions thread) in that original post with step by step instructions on how to test your own designs. For example something like:. (1) Install mods A, B, C. (2) Install thhes saved game .zip. (3) Stop the trains by doing A, B, C ... (4) Delete the intersection and setup your own. (5) Start the test by doing A, B, C. (6) Wait 15 minutes. (7) Get the results by looking at X. ----. That way when someone wants to test their own designs you would just give them that link and they would be able to follow the instructions and test without bothering you or the OP.

I fully agree.
I made a way more easier to understand savefile including sets/profiles with nuclear fuel.
I didn't move the 15min test result, but you don't really need it as the result after 24 min or 500 min is more accurate.
I also think the recommended mods should be on the savefile so that you can easy sync them.

How it works without my changes:
Start/stop. Turn the combinator with -10K green lights off to start. Turn it on to stop.
Reset counter. Turn the inserter
Check results. Hover over the substation. R=trains/min
Change profiles, Set p= 1-5, see the map for what the different profiles are.

WIth the new savefile it is like this
Start/stop, turn green inserter
Reset counter, turn blue inserter
Check result on a closer substation
Change profiles with the constant combinator.

You can now start/stop it from map view=)

Also now everything you are not supposed to touch is on hasard concrete. ( in the controller area)
I also added information on the map to explain how to control the test bench.

I think I can make those instructions work, thanks for writing them down. Unfortunately I am very busy with work at the moment so it might be a couple days before I can try it.

I will attempt a couple of flavors of outer lane right turn to see how they work.

I think I will not mess with the additional waiting lanes at this time, as that would be for a significantly different design and not very relevant to the overall rail line strategy that this intersection is mainly created for (inner 2 lanes primarily for u-turns, next 2 lanes are the main traffic lanes unless congested, then outer "exit lane branchnes" approx 8 chunks long for exits/entries to factories). I postpone designing a beast with more waiting bays for sometime in the future.

@hansjoachim: I was able to test your 2.1 rig and instructions. They are quite clear and work great.

You should see about having @aaargha include it in the original post, or make a separate thread with the instructions so that you can point people to them.

---

I think I will not mess with the additional waiting lanes at this time, as that would be for a significantly different design and not very relevant to the overall rail line strategy that this intersection is mainly created for (inner 2 lanes primarily for u-turns, next 2 lanes are the main traffic lanes unless congested, then outer "exit lane branchnes" approx 8 chunks long for exits/entries to factories). I postpone designing a beast with more waiting bays for sometime in the future.

The waiting bays I added keeps the intersection deadlock free even with longer trains. If the trains are small enough for the waiting bays the throughput is increased. If the trains are too long, the throughput is the same as without them.

Yes, I know that adding those waiting bays would benefit shorter trains while making little or no difference for the bigger trains.

It gives me ideas for the next design, but it just didn't seem worth it for *this* design. Especially since it no matter what I did I could not increase the right turns beyond the 35 without significant changes that turn it into something entirely different. That will be for the next design. I am running a final test and will post my official design for it.

Features:
- Compact.
- Respectable performance for a compact intersection.
- Adaptable to trains of various sizes:
--- Add a straight segment that can fit your longest train on each of the 4 ends.
--- Add a lane changer after the straight segment. It can be a compact lane changer with negligible performance difference compared to the more sophisticated ones.
- Designed with a well planned network in mind (excellent straight and left turn performance for a compact LHD intersection).
- Includes turnarounds from inner tracks.

You can find faster intersections (most of them quite a bit bigger). You can find more compact intersections (most of them not as flexible). You can definitely find better looking intersections. This intersection was designed balancing all of those desires as well as flexibility and support for various designs that improve overall rail network behavior.

Best "real use" performance of this intersection comes from the following track philosophy:
--- Center lanes dedicated to direction change (and traffic overflow).
--- Outer lanes as the main high speed lanes.
--- Short additional set of tracks for exits/entries to your factories (never cross tracks), putting splits/merges there, always leaving at least one train length between your exits/entries and the merge points to your main lanes.

In it's current state I don't think it would fit into aaarghas lists of 4-way intersections.
As it currently doesn't allow right turns from outer lanes. Therefore it isn't a true 4-lane 4 way intersection.

Easiest change would be to add right turns in the way you proposed or add lane changer to the blueprint.

In it's current state I don't think it would fit into aaarghas lists of 4-way intersections.
As it currently doesn't allow right turns from outer lanes. Therefore it isn't a true 4-lane 4 way intersection.

Easiest change would be to add right turns in the way you proposed or add lane changer to the blueprint.

The intersection (when you include all 3 pieces - that are separate so that it can support trains of any length) does support right turns from the outer lane. You are only thinking of one of the pieces (the main one).

The three pieces are:

- The core piece.
- The straight leading bays - as long or longer than your longest train.
- The lane changer - either the simple and compact one in the screenshot or a fancy and much bigger one (the difference in trains per minute is only 1-2 trains per minute, so the choice depends on how much space or throughput is desired).

So, it either fits in the thread as is - in three pieces - or I can easily include both a 1-4-1SD(same direction) single blueprint (that loses the *any length train ability*) plus a 3 blueprint version that players can put together for trains of any length. Which of the two approaches can be aaargha's choice,

Finally, although unnecessary, I tried to satisfy your desire to have a right turn from the outer lane right in the core (which would have freed it from needing the lane changer piece). In the end I decided to go with this version because the other options either performed worse or morphed the intersection into something entirely different that deserves to be a separate intersection design. Also, this particular design fits a specific overall network layout niche (a network with very few intersections, mainly only straight, left turns and direction reversals, prioritized lanes that shift traffic to the outer lanes of the 4 and other related features - which is only partially measured by these tests) particularly well, and I wasn't willing to compromise on those abilities for the sake of looking good on this particular set of tests. If you are interested in understanding that form of design, check out and play with this blueprint book https://factorioprints.com/view/-LPOOJ-GsdY4h7KTnHgc that assumes a mainly linear primary line with only an occasional intersection. In that design priorities are such that traffic naturally lines up on the high speed lanes, leaving the return and exit lanes largely free for those functions while also serving as overflow to handle congestion. So, it should be obvious why I didn't want to compromise the intersection's ability to function optimally when used in that kind of design.

So, it either fits in the thread as is - in three pieces - or I can easily include both a 1-4-1SD(same direction) single blueprint (that loses the *any length train ability*) plus a 3 blueprint version that players can put together for trains of any length. Which of the two approaches can be aaargha's choice,

Sure, lets see what @aaargha thinks.
The thing is that he hasn't been active in this subforum for awhile. He has promised to get back to it when he finishes his other projects.
I want to help to get intersections ready for being posted, so that whenever he comes back he doesn't have such a large backlog. When he is back, lets say a couple of months, he might want some changes to add an intersection to the list. If he then makes a comment and you have forgoten about the subforum and doesn't respond, the intersection then probably won't get added to the list.

So, it either fits in the thread as is - in three pieces - or I can easily include both a 1-4-1SD(same direction) single blueprint (that loses the *any length train ability*) plus a 3 blueprint version that players can put together for trains of any length. Which of the two approaches can be aaargha's choice,

Sure, lets see what @aaargha thinks.
The thing is that he hasn't been active in this subforum for awhile. He has promised to get back to it when he finishes his other projects.
I want to help to get intersections ready for being posted, so that whenever he comes back he doesn't have such a large backlog. When he is back, lets say a couple of months, he might want some changes to add an intersection to the list. If he then makes a comment and you have forgoten about the subforum and doesn't respond, the intersection then probably won't get added to the list.

To prepare for @aaargha, here is a better presented submission.

--------------------

First, the real Bulldog Tic Tac Toe intersection.

PART 1: The core intersection piece.

PART 2: Arm pieces (place enough of these so that your arms are longer than your longest train).

PART 3: Compact lane changer elements (use two at the end of each arm pointing in opposite directions, to ensure lane changes from every lane to every lane).
You can skip these and replace with the lane changer of your preference, although the TicTacToe intersection throughput tests showed very little difference between these and the more powerful lane changers.

PART OPTIONAL: Main line segment (repeat end to end as many as needed, and its ends merge with the tic tac toe's intersection lane changers)
This is not strictly part of the intersection but works very well with it, boosting its performance in real-use scenarios.
In real use traffic will avoid the outer exit branches and the central turn-around lanes unless it really needs to go there or the high speed lane is occupied (differences in speed with merging traffic will lead to an eventual merge into the high speed lane).